Flying makes us nervous because the stakes are very, very high. Even though we know a plane crash is unlikely, if it does happen, the outcome is probably not going to be good.

If a flight is going to have problems, statistics show that it’ll likely be during takeoff. Knowing this, Cheng listened to a recording of a jet engine revving up while sitting on her couch at home. She began to associate the sound with the comfort of home.

Our fears are often rooted in some kind of rationality, says Cheng. And sometimes math can help us dissect them.